mueller



- M. L. MUELLER METHOD AND APPARATUS Foil KIL. N DRYING original nlegJuly 2o. i921 a 'shun-shut. 1

l1. ...vl

.'Nov. 1s,A v1924. Re'. 15.94.6 M. l.. MUELLER Y `KETHOD AND APPARATUS vFOR KILN DR'YNG original Filed .July 2Q 192x s shun-shut 2 3mm/fo@ Man'z Maak/2",

atto: wu 3 Nov. .18.1924- Re. 15,946

M. L. MUELLER l METHOD AND APPARATUS Fon KILN DRMNG-` original Filed July 2o A '1921 s shun-shut 5 www awww, S

Reuma Noa is, 1924.

UNITED s 'r-.xrlazsy PATENT lorries.

IORITZ L. MUELLER, OF- SEATTLE, WASHINGTON, ASSIGNOR TO NORTHWEST BLONIEJR. i KILN OO., 0F SEATTLE, WASHINGTON, A CORPORATION 0F WASHINGTON.

METHOD AND APrABATUs ron KILN DRYIN."

-Original No. 1,487,385, dated November 28, 19112, Serial No. 48G,282, led July' 20, 1921. Application for reissue led August 12, 1924. Serial No. 731,677.

lo. all whom it may concern:

Be it known. that I, Monrrz L. MUELLER, a citizen of the United States, residing at .Seattle, in the county of King, State of Washin on, have invented certain new and useful i paratus for Kiln Drying, of which the following'is a. specification. n My invention relates to methodof operating the same.

The objectof my invention is to produce a kiln designed especially for drying lumber but capable of being used for drying other materials, and a method of operating such kilns, which apparatus and method are vdesigned to be an improvement over the existing art. Y.

The characteristic feature of the process consists in providing means whereby a posi;

tive circulation maybe secured in the kiln and whereby a certain small percentage of the ar after having passed through the kiln and absorbed moisture from the contents of-v the kiln, will be discharged from the circulation and its place taken by a like amount 1^ of air drawn from an outside source.

Another object ofmy invention is to pro-l vide an apparatus which is simple and cheap in its construction and whereby better and more even distribution and circulation of the air is secured throughout the contents of the kiln. y'

seen from al study of the following specification and the accompanying drawings.

The features of my invention which `I believe to be, new and'upon which Idesire to ythe manner of using the same which consti y tutemy invention. 45

Figure l is a plan view of the air distribut-ion system of the kiln, the walls of the kiln being shown in section.

Figure 2 is a longitudinal sectional ele- 'vation of that part of the which contains the air distributing pipes.

Figure is 'a cross sectional view of a kiln having my inventioninstalled therein, illusl provements in vMethods and i Ap-` dry kilns and the.

trating theJ location of the parts employed for producing -a positive circulation.

Figure '4 .is a cross sectional view of a kiln of my construction in which the air distributing pipes are located in somewhat different relation and the mannerl of circulating the air throughthe lumber is also somewhat diferent.

The accompanyin' drawings show a kiln 1 which is, or may loe,inmany respects of standard construction. The kiln chamber is shown'as being constructed of such size and shape as to receive loaded cars or trucks of lumber for the purpose of drying the same. It is, therefore, provided 'with track rails'lO which extend through the kiln and upon which lumber piling trucks ll are mounted t0 run. i In the device as shown in"A Figure 3 the lumber is shown asplaced horizontally upon the trucks and provided centrallywith an4 preferably tapering from the 4bottom towards the top. l It isto be understood that f in forming the piles upon the trucks, cross strips are placed betweenv thel layers of lumber thus providing an air circulating passage at-each side of each la er of lumber.

In a distributing system aving the pi esl located and used as is contemplated in 1g- A 4, ure 3, the central pipe 2 is the air discharge Other obejects -of my invention may be.

pipe for the'air which is'dschargedjfrom the heater into' the kiln for the purposeof drying the lumberl or other product con-` tained therein. The pipe 2 has a large nunr ber of .discharge slots or holes 20 placed rather closely together'and distributed along the length of the pipe. These are in the top wall ofthe pipe. In consequence, the air discharged through these openings 20 is dis charged directly into the chimney 12 which has been formed at the center of the load of lumber on the itrucks.. The air passing up into this chimney passes there-from laterally in opposite directions between the layers of boards and is ydischargedat thel sideof the pile of lumber, thence flowing downwardly at eachfside of the kiln and is drawn into the suction or discharge pipes 3 from which it is withdrawn to .the heater.

'Ihe suction 'pipes 3 are shown as being round in -cross section. The round sectionis h'owever not an essential altho h it is a convenience on. the score of ease an economy of manufacture. The pipe asa whole is made Yup of a-number of units which are p l 'vely of somewhat smaller diameter as theyare located farther away from' the at which said pipe is connected with the suction producing 'meanbf,`f As shown in the drawings the connection `with both theair lsupply and the suction pipe is at the center of the length of the kiln. It may however, `be made at any point which has been found suitable and is desirable.-

Whiele for-pur oses of explanatiom-I have illustratedthe that the air flow is in the clear cut and well defined paths .designated by said arrows. UponV the contrary "the central -vertically directed jets of air actas injectors, drawing into themselves air from `the main body of air -withn' the kiln and more or less .air from the return Vstre"ams,.until 'the whole body of air vand water" vapor within the kiln is in circulation. The result offthis is that materiell lmore air'is `circulated than is' actually. andled by the fan, whereby I am able to increase the volume of 'the drying mediumwith'a minimum size and capacity blower or fan. This results in economy in first cost and in economyin powerconsump-4 tion. Furthermore the air drawn into the ydischarge streainhas its temperature raised by contact and intermixture with. such stream and .thus the -heater 4 exercises its effect upon a much larger volume of air than f ever directly contacts with it. By creating the condition above lset forth i. e. one whereof the kiln it is assured that each land every' dried will be subv in; dryingmedium of large volume 'is uniforlnlyv circulated' throughout the whole area part ofthe lumber bein i ]ected to substantially t e same drying i117 yThe v.discharge open fluenoe,whereby uniformity in product, Va

'mostgdesirable result, is achieved. v

- air dischar pipe 2 is madetaperin'g or in epth from its main sup- -ply pi 121. vin either direction althoughv pref'enlyolf uniform width.v This pipe is shown .as being of olygonal .Y cross. section, the same being indi k,cated as' a rectangle. v n `.8 I'6 all located in thotopwall ofthe .pipe' r['he suction SIBLShOWn-as being' of round cross section. These are progressively smaller in diameter aathy are removed from the point where is connected with the circution in size is Iown as being secured by making the pipe up ofa number'of sections, which sections are lrogressivel'y of smaller diameter. This di erence in, diameter' is enou h so that if the pipe sections be se cure 'to each other -llongfoue side, ythere irection of the air currents A .by the arrows it is not to be understoodl mechanism. This reduc` will. be'- formed.. between the telescopic ends of the pipe acrescent shapedopening.' Sueh a. openings are relied upon for passing air into Vthe suction ipe 3.

`Outside o the kiln is lQcated-aheater 4 and afan 5 or any suitable means for 'producingy a positive circulation of the 'ail'. The heater ,isconnected with the air withdrawing. lor suction pipes 3 of the kiln by means of ay iiue 30. The fan 5 isconnected with`v the air supply pipes 2 by means ofr flue 21. The heater andthe fan are connected-so that the fan draws its air supply from'the heater' andthen forces it into the kiln.

The mechanism whichis described consti'- i tutes' one form of closed circulation system for dry kilns.- -It is not contemplated that this system be operated continuously as a perfectly closed system.v I have found that if. a small percentage of the air` of the kiln -be dischar ed or wasted after it has passed through 't e fdry kiln, it will eventually. carryof a very lconsiderable amount of the-A moisture whichhas been extracted from the lumber by the heat. The amount of air thus 'discharged must, however, be replaced. f This is done .by admitting the requiredamount o fair to the system, preferably at a' point lJust prior to its entrance to the heater 4.' vFor this `purpose I have shownl in the hood 41 which connects the heater with the suction flue 30, an opening which is normally covered' by a slide, as ft2. By properly adjusting lthe slide the opening may be varied in areaor entirely closed.

The amount of air drawn into the system n i at i this point should correspond with `the amount ofairwithdrawn from the system atano'ther point or points. By withdrawf ing a small` amountl of air and replacing this with air drawn from an outside source,

excessive charging of the' air'in the kilnis prevented and heat units are conserved. I have found it sufficient to provide means foradmitting' a small amount of air to thev heater. As there is'a certain amount of suction at this Apoint this may bej done by which vwill communicate with the external air.

I have also found -that in kilns of -normal or usual construction there is suili'cientleakage of air, if lthe pressure inside rises .even a quite nnapprecia le amount, that it is unnecessary to provide special means for the discharge of la small amount of air from the providing. any suitable type ofv openinglrw kiln. For this reason Ihave notv shown any l s cial air discharging .means except as the .'12s

ue 13 serves for t is purpose. Special dis- \charge o nings of an suitable type maybe provlde kilns are lusually constructed natural leakage will be' found suicient.

-.` In thefkiln as illustrated 'in Figure 4 the if this is t ought desirable. As

lao

lumber trucks are supposed to be loaded with lumber which has been piled on edge. In this case I prefer to reverse the locations of the air suppl and discharge pipes. this case I pre er vto have the air supply pipe divided, one being placed at each side close against the wall of the kiln. The air suction pipe or that which. isl used towith-A draw air from the kiln is -in this case located centrally beneath the kiln. In such case as this the hot air discharged from .the fa is blown upwardly intothe passugeways exist"- ing between the sides of the load and the side walls of the kiln. This air enters between the lumber'at the top of the pile and is drawn downwardly and into the air discharge pipe 3. The position of these pipes may be shifted as is thought best for different methods of piling the lumber.

Experience has shown that the air 'distributing means employed secures a substantially uniform .distribution of air throughin o out the length of the kiln. -Also that by continuously withdrawing the lumber and replacing this with unsaturated air,the necessity for condensing the moisture is elimi' nated. This retains the heat-in vthe air except for the small amount contained in the discharged air and thus produces economy ration. v

W at I claim as my invention is:

l. In combination a kiln a lu'mber car trackway'therein; a discharge conduit centrally disposed beneath the trackway and having a plurality of openings in its upper side. said conduit being gradually reduced in height froman intermediate portion toward its opposite outer ends, suction conduits having a plurality of inlet openings disposed upon opposite sides ofthe trackway and gradually reduced in capacity from an intermediate portion toward their ends, a circulating fan and casing therefor, and conduits connecting one side of said fan casing to the suction conduits and the other side of said fan casing to the discharge conduit Vsaid suction units being composed of a plurality of successively smaller circular.

sections the vjoints of which are so loosely Inv lumber-in a kiln having al sive layers of lumber spaced from each other to leave a plurality of lateral air passages therebetween, said lumber being so piled as to leave a` longitudinallyY elongated central flue in each pile of lumber which is con- 1 stricted upwardly and substantially closed y at`the top to thereby cause air delivered into the lower part of said flue to pass through said lateral openings and introducing said trucks into said kiln upon the tracks so that air .from the air discharge conduits will be delivered into the elongatediues of the piles of the lumber at whatever point upon the trackway they may be positioned.

'3. The herein described improvement in Vthe art of drying lumber which consists of disposing the lumber substantially hori- Zontally in4 a kiln with the pieces thereof in spaced relation to leave a plurality of air passages therebetweenand introducing air to and withdrawing air from said paages in such manner as to set up a circulation of air between a point in substantial central alinement with the pile of lumber and spaced' points disposed outwardly of the first named point and infsubstantial alinement with the sides of the pile of lumber, the incoming air acting after the manner ofan injector, drawing into itself air from the main body of air within the kiln and air from the return streams so that some of the air is'recirculated before passing from the kiln and materially more air is set in motion than is discharged into the kiln. Y

In testimony whereof I hereunto aiiix my signature.

MORITZ L. MUELLER. 

